Process for the reduction of halogenated hydrocarbons



Patented May 10, 1927.

UNITED STATES 3 I p 1,627,881 PATENT OFFICE.

ALFRED FELIX SEBASTIEN BELLONE, OF LYON, FRANCE, ASSIGNOR TO 'SOCIETE GHIMIQUE DES USINES DU RHONE, OF PARIS FRANGE.

rnocnss non. THE nnnuerron or naLoenna'ran mnocannons.

No Drawing. Application filed January 28, 1924, Serial No. 689,168, and in France November 21, 1928f It has been known for a lon time that halogenated hydrocarbons can he reduced into hydrocarbons halogenated to a lesser the action of certain metals.

tained (see, for instance, the patents taken in U. S. A., No. 753,325, of 9th October, 1902, No. 1,101,025, of'26th July, 1912, and

' No. 1,311,329, of 8th June, 1914) require the use of iron in the form of a very fine powder, the manufacture of which is itself very costly.

Applicant has discovered that the reduction of the halogenated hydrocarbons can be effected in a'very simple manner and with quantitative yields, by agitating, at a suitable temperature,-the halogenated hydrocarbon to be reduced with ferrous hydroxide in a basic medium. 3

The reaction may be represented diagrammatically by the two following equations, where X represents a halogen atom and R a radical which maybe or may not be halogenated:

These equationscorrespond to the replacement of an atom of halogen by an atom of hydrogen, but the reaction is equally applicable to the progressive replacement of the halogen atoms contained in a poly-halogenated .derivate. For instance, starting from C C1,, one can pass to chloroform or to methylene chloride, and so on, according to the quantity of ferrous hydroxide emplgf ed;

The quantity of water to use is so, as a minimum, that correspondin% to the theoretical needs of the reaction, ut it may be much larger, for 'instance- 100 times larger,

inorder to dissolve certain substances present or for any other" purpose, without adversely affectmg the 'reactlon. 1 Too great .a dilution could, however, in certain cases entail secondary reactions. 1

The additional quantity 'of base used must not depart too much from the quantity which must combine with the halogen taken from the halogenated derivative undergoing reduction, if one must not be. led to a consumption of ferrous hydroxide greater than that derived from theoretical considerations. Any base may be employed, for instance alkaline or alkaline-earth bases, including magnesia, being guided in the choice by questions of cost. However, weak bases will be advanta eously preferred to strong ones, such as soda or potash, when the required: product will be sensitive to the action of these strong bases, as is the case, for in-' stance, with'chloroform. One can even replace these bases by weak salts of acids, such as carbonates and such like.

It is to be noticed that the reduction is not unfavorably influenced by the presence of any neutral or basic salts such as, for instance, those which contaminate'or may contaminate the ferrous hydroxide repared by the usual known methods. It. ollows, as a result of'evident practical importance, that the ferrous hydroxide may,'without inconvenience, be prepared in the midst of the medium itself undergoin reaction, before or during the reaction. it is also not unfavorably influenced by the presence of any liquid, organic or 1norganic,-neutral or alka-' line, chemically inert to ferrous hydroxide, to the halogenated hydrocarbon which is to be reduced, or of the product or products of its reaction, which may be added to the reagents for anyparticular purpose, for instance for extracting the final product of i the reaction or protecting it from theaction of the reducing medium as it is generated.

The reduction as a rule starts at the ordinary temperature. It is enhanced by good mechanical stirring of the reacting medium. It may be accelerated by heating, through any the heating arising out of the reaction itself, or on the contrary it maybe retarded by.cooling.

The reduction may bepushed to its ultimate end or, on the contrary, it may be interrupted before the. whole halogenated of the known suitable means, besides I hydrocarbon to be reduced has undergone the desired transformation. This latter operative method may be thought to be preferable, for instance, when the product of the reaction is itself liable to be reduced by the ferrous hydroxide.

The product or products of the reaction may be separated from the reacting medium by ordinary distillation or steam distillation, or any other suitable manner.

The apparatus used for the reduction comprises, for instance, a vessel of wood or metal, preferably closed if volatile bodies are either undergoing reaction or produced during the operation. It is provided with anefiicient stirrer and, if need be, with any known suitable means of heating or cooling,

and with a thermometer and any other means of following the reaction. In the case of the reduction of a'volatilebody, the apparatus is advantageously provided with a reflux condenser, connected to a distillation and, as in .both cases,

column or to any known and suitable condensation device, for instance, if it is desired to separate the products ordinary distillation or by steam distillation.

The ferrous hydroxide necessary to the re- 4 duction may be obtained economically, either by electrolysis or by any chemical means, its preparation may be carried'out simultaneously with the reduction, the process which constitutes the object of the present invention may be worked by either of the four following general types of operating methods:

I. A suitable electrolyte, for instance an aqueous solution of a neutral or basic salt, is placed with the halogenated hydrocarbon to -be reduced in an electrolytic apparatus with soluble iron anodes. This electrolytic apparatus may be, for instance, an ap aratus of the above type the metallic walls of which will act as cathode, iron anodes passing through the cover (if an a The current is caused desired conditions of voltage and intensity, for instance, the conditions which are known to be most favorable to the generation of ferrous. hydroxide. a

The reaction begins and proceeds by itself or owing to suitable heating. It is stopped at the desired stage and the product or products by anysuitable process.

II. The ferrous hydroxide, prepared by, any electrolytic method but, except for the presence of ,the halogenated hydrocarbon .to be reduced, kept isolated b any suitable means from the medium in wliich it has been produced, if desired, or mixed with all or; part of this medium, is introduced in a separate reduction apparatus which has been preliminarily filled with 'the halogenated hydrocarbon to be reduced and a suitable quantity of basic solution.

Generally, the reaction begins by itself; if not, itcan be started by suitable heating. The operation is completed as in I.

of the reaction by to pass under any;

of the reaction are separated III. A solution of a ferrous salt is introduced in the reduction apparatus together with the halogenated hydrocarbon to be reduced. The ferrous solution, if desired, may be prepared in the apparatus itself by dissolving iron in an acid. The ferrous hydroxide is precipitated by any known suitable base or basic salt or solution thereof. The operation is completed as in II.

IV. The halogenated hydrocarbon to be reduced, water or any other suitable medium and the necessary quantity of base are introduced in a reaction apparatus, and to the mixture is added the ferrous hydroxide prepared separately by any method, either alone, or in neutral or basic aqueous or other suspension, and, for instance, with the whole or part of the medium Within which it has been prepared. The above order, in which the substances are introduced, may be altered or reversed. The operation is completed as in I In order'to illustrate the present invention, applicant gives below examples of preparation of chloroform by reduction of carbon tetrachloride, according to every one of the above methods.

It will be well understood that these examples do not in'the least restrict the invention, and do not preclude in any way any' modifications which a man trained in the art could device according to what has been said above.

Example I.In a tight metallic apparatus, provided with a stirrer and heating coil, and connected to a condenser, are introduced 1,500 c. c. of. an electrolyte, such as, for instance, a solution of calcium chloride, the concentration ofwhich is equal to that corresponding to maximum conductivity (that is, about 25%), milk of lime; containing 150 grammes of lime, and 500 grammes of carbon tetrachloride.

The apparatus acts as cathode. .Iron masses properly insulated from the cover, pass through or are suspended from the latter, and constitute soluble anodes. A suificient current is caused to pass to obtain the I required degree of reduction,

of the tetrachloride is reduced.

'Ihe chloroform is then separated by distillation.

Emample II.In an electrolytic apparatus of suitable shape, containing brine (which may advantageously be circulatin a mass of scrap iron, constituting the ano e, is acted lipon by an electric vcurrent (400 ampere hours, for instance). The base formed at the cathode precipitates an equivalent quan- 'tity of ferrous hydroxide which can be separated from the ulk of the' electrolyte by a suitable means, such as decantation, centrifugation, etc.

This ferrous hydroxide is afterwards transferred to the reduction aPParatus,

where it iscaused to react with 500 grammes of carbon tetrachloride in the presence of g'amnms of hydrated barium hydroxide, g H): s z

mple'IIl.-1,80O kilogramme of crystallized ferrous sulphate, 2,000 'c. c. of water,

1,7 50 c. c. of caustic soda of 36 B., and 500 tetrachloride are introduced into an apparatus analogous to the former,

and gradually heated. so as of chloroform when the reaction is ended.

Example I 72 -400 grammes of iron'are caused to be reacted upon by sulphuric acid containing 700 grammes ure acid in a separate apparatus. The errous hydroxide, subsequently precipitated by 360 grammes of magnesia, 1s separated more or less completely from the medium in which it has been generated, and is transferred to a reduetion apparatus in order to react with 500 grammes of carbon tetrachloride.

What I claim and desire to secure by Letters Patent is:

1. The process of hydrocarbons and tives of or nie com unds treating sai hydrocar ns-with ferrous hyreduction of halogenated poly-halogenated derivahydrocarbons and but without iron anodes. The mix-' ture is stirred to arrive at the temperature of distillation and of a substance consisting in droxide .in the presence of water and of a substance having a basic reaction, thereby substituting progressivel hydrogen for the halogen atoms insaid ha ogenated hydrocarbons and poly-halogenated derivatives.

2. The process of reduction of halogenated polyhalogenated deriva tives of organic compounds according to claim 1, characterized in that the ferrous hydroxide is repared in the reduction apratus itse f.

3., The' process of manufacture of chloroform by treatin carbon tetrachloride with ferrous hydroxi e, in the presence of water 4. The process of manufacture of chloroform by treatin carbon tetrachloride with ferrous hydroxi e in the presence'of water and of lime.

having a basic reaction.

5. The process of reduction of halogenated hydrocarbons and polyhalo'genated derivatives of organic compounds according to claim 1, characterized in that the ferrous hydroxideis prepared in the reduction liquid itself and this, before the introduction of the halogenated body intended to be reduced.

ALFRED FELIX SEIAS'I'IEN. IELLONE.

In testimony whereof, I afiix my signature. 

